refactor(core): Ensure that previousOrParentTNode always belongs to current TView. (#38707)

`previousOrParentTNode` stores current `TNode`. Due to inconsistent
implementation the value stored would sometimes belong to the current
`TView` and sometimes to the parent. We have extra logic which accounts
for it. A better solution is to just ensure that `previousOrParentTNode`
always belongs to current `TNode`. This simplifies the mental model
and cleans up some code.

PR Close #38707

packages/core/test/render3/di_spec.ts

@@ -228,7 +228,7 @@ describe('di', () => {
       const contentView = createLView(
           null, createTView(TViewType.Component, -1, null, 1, 0, null, null, null, null, null), {},
           LViewFlags.CheckAlways, null, null, {} as any, {} as any);
-      enterView(contentView, null);
+      enterView(contentView);
       try {
         const parentTNode =
             getOrCreateTNode(contentView[TVIEW], null, 0, TNodeType.Element, null, null);